Drives are needed for certain applications, e.g. distributor rollers in printing machines, whereby a rotational movement can be superimposed with a short-stroke linear movement. A so-called combination drive, whereby an electric (torque) motor is combined structurally with a linear motor, enables such superimposed movement to be produced. Both sub-drives each require a feedback sensor, which must not be influenced by the other movement in each instance. This means that the linear position sensor cannot be influenced by the rotational movement of the drive and the rotation sensor must operate independently of any linear movement.
In the printing industry however with the combination drives mainly used for at present for distributor rollers the linear movement is generated from the rotational movement by way of a mechanical system, e.g. cam plates, connecting rods, etc. In this case, only a conventional rotation sensor is required, which is integrated into the motor. It detects the rotational movement and the linear movement is automatically derived from this.